Production or treatment of artificial materials



Patented June 2, 1936 PATENT OFFICE PRODUCTION OB. AB'IIFI TREATMENT OF CIAL MATERIALS Henry Dreyfus, London, England No Drawing. Application April 15, 1930, Serial No. 444,620. In Great Britain May4, 1929 11 Claims. (CI- 18-54) This invention relates to the manufacture or treatment of artificial materials particularly filaments, ribbons, films, threads, yarns, fabrics and the like.

According to the present invention silica or hydrated silica, hereinafter included in the term silica, is incorporated in artificial materials particularly filaments, yarns, threads, fabrics or the like of all kinds whereby certain desirable properties are imparted to the materials.

The new filaments, ribbons, films, yarns, threads and like materials containing silica have in general a reduced or subdued lustre. The presence of silica in the materials may also confer other valuable properties on them, for example, in the case of materials made of or containing cellulose esters, increased'resistance to heat.

The introduction of silica into filaments, ribbons, films, threads, yarns, fabrics, or other artificial materials in accordance with the invention may be efiected in any suitable manner, for example, finely divided silica may be incorporated in solutions from which artificial materials are to be prepared. In general, however, the introduction is very conveniently eifected by the interaction within the materials of appropriate reagents capable oi yielding silica.

Reagents capable of forming silica may be introduced into the filaments, threads, or the like in any convenient manner and at any suitable stage in or subsequent to their manufacture. A particularly convenient method is to introduce one of the reagents into the solutions intended for spinning into filaments, or for forming into ribbons or films; as an alternative the said reagent may be introduced into the already formed filaments or the like. In either case the second reagent necessary for the formation or liberation of silica within the materials may then be applied to the materials and may be for example in' the form of a liquid bath or in the form of a gas or vapour.

Any suitable reaction may be utilized for the formation of silica within artificial filaments, threads, or the like in accordance with the invention but mention may especially be made of the reaction between a soluble silicate, e. g. an alkali silicate, and an acid, whether inorganic or organic and the reaction between an organic silicate, e. g. an alkyl silicate, and an aqueous reagent.

The choice of reagents to be used in any particular case will depend on the nature of the material of the filaments, threads, or the like and on the method to be adopted for incorporating the silica. Thus in the case of artificial filaments and the like spun from aqueous spinning solutions, for example viscose solutions, a very convenient method of producing silica-containing filaments, is to incorporate a soluble metal 5.. silicate, e. g. sodium silicate, in the spinning solutions and subsequently to treat the filaments with an acid. Where an acid spinning or..coagulating bath is employed, as for example in the production of artificial silk by the viscose l0 process, a further special acid treatment will of course not be essential.

Where, however, the spinning solutions are substantially non-aqueous as for example in the case of spinning solutions comprising cellulose 15 acetate or other cellulose esters dissolved in acetone or other organic solvent, the aforementioned alkyl silicates are particularly useful reagents for the purposes of the present invention.

The alkyl silicates possess the advantage that 20 they are readily soluble in organic solvents and are easily incorporated in spinning solutions containing organic solvents, for example, the solu tions of cellulose acetate or other cellulose esters or cellulose ethers used for conversion into arti- 25 ficial silks by dry spinning processes. Among the alkyl silicates which may be used are tetramethyl silicate, tetraethyl silicate, tetra-amyl sill cate, hexamethyl disilicate, and hexaethyl disilicate, For incorporation in cellulose ester or ether 30 solutions intended for dry spinning the alkyl silicates of comparatively high boiling point, e g. above 0., are particularly suitable.

Thus, in preparing filaments of cellulose acetate or other cellulose esters or cellulose ethers con- 30 taining silica in accordance with the invention, a solution comprising the cellulose ester or ether and an alkyl silicate dissolved in acetone or the like may be spun into a heated atmosphere and the resultant filaments, threads, or the like treated with an aqueous reagent so as to decompose the-alkyl silicate withliberation of silica within them. In this manner there may be readily produced artificial filaments, yarns, and other materials exhibiting a pleasing dull lustre.

Alkyl silicates may likewise be incorporated in substantially non-aqeous solutions of cellulose esters intended for spinning into liquid coagulating baths, the second reagent necessary to effect liberation of silica being applied in the coagulating bath itself or in a subsequent operation.

In utilizing organic silicates in the aforesaid manner for the purpose of introducing-silica into artificial materials, particularly filaments of cellulose esters or ethers, a special treatment may be necessary in order to effect decomposition of the organic silicate in the materials. Thus thematerials containing organic silicate may be treated in aqueous, baths to which have been added substances having a solvent or swelling action on the materials or which otherwise assist the action of water thereon. For example there may be employed as' treatment baths aqueous solu tions of organic or inorganic acids for example hydrochloric acid of 1-5 per cent, e. g. 2.5 per cent strength, or acetic acid of 10-30 per cent strength.

As previously indicated artificial filaments.

threads, yarns and other materials containingsilica may also be produced in accordance with the invention by incorporating finely-divided silica in the solutions of cellulose o'r cellulose derivatives, from which the filaments and the like are to be made. For example silica may be precipitated from a soluble metal silicate by means of acid, or liberated from an organic silicate by hydrolysis with dilute acid or alkali, washed with water and with acetone and added to a solution of cellulose acetate in acetone prior to the conversion of the latter into filaments. In this manner also filaments exhibiting low lustre may be obtained.

The invention is not restricted to the-introduction of silica into artificial filaments during the course of their manufacture for, as previously indicated, the said introduction may be effected in the already formed filaments and threads, or in any goods made therefrom, for example knitted or woven fabrics. The introduction may be effected by incorporating a suitable reagent in the materials and then treating them with a second reagent capable of yielding silica by interaction with the first. Thus, for example. a fabric made from yarns of the regenerated cellulose type may be impregnated with a solution of a soluble silicate. e. g. sodium silicate, for example by passing through a bath of sodium silicate or padding with a solution of sodium silicate, and then sub- Jected to the action of an acid, e. g. an organic acid.

In case it is desired to introduce silica into already formed filaments, yarns, fabrics, etc., made of or containing cellulose acetate or other organic esters or ethers of cellulose it is advisable that at least one of the reagents is applied to the material while the latter is in a swollen condition. The swelling of the cellulose ester or ether material may be accomplished by addition of suitable swelling agents to one or other of the baths unless one or other of the reagents is itself a swelling agent for the cellulose derivative when such addition may be unnecessary. For example a fabric made of or containing cellulose acetate yarns may be treated by padding or otherwise with an aqueous solution of an organic acid, e. g. oxalic acid, tartaric acid, or benzene or other sulphonic acid. In general the organic acid will be sufilciently absorbed by the cellulose derivative without the presence of any additional swelling agent but the addition of such agent is not excluded; the acid impregnated fabric may then be subjected to the action of a soluble metal silicate to effect formation of silica within the said fabric.

' Though the alkyl silicates are most usefully applied as additions to non-aqueous spinning solutions the resulting filaments being then subjected to the action of aqueous reagents capable of yielding silica with the alkyl silicate, the invention is not restricted to their use in this manner. They may also be used for. the incorporation of silica into already prepared filaments or the like, for example a cellulose acetate or other cellulose ester fabric, may be treated with a solution an alkyl silicate in an organic 5 solvent such as alcohol, ether, or acetone, the alkyl silicate being subsequently caused to react with water to eifect production of .silica within the filaments.

The invention is applicable to the production ortreatment of artificial filaments, threads,

yarns or the like, or materials made therefrom, of all kinds, for "example filaments or the like made of cellulose esters. e. g. cellulose acetate, formate, propicnate, or butyrate, or of cellulose ethers, e. g. ethyl, methyl, or benzyl cellulose, or made of regenerated cellulose.

The following examples show the best method known to me for carrying the invention into effect but are not to be regarded as limitative:

Example 1 A solution is prepared containing per cent of cellulose acetate and 1.8 per cent of ethyl si1i-' cate in acetone of 99.8 per cent purity. This 25 solution is then spun into filaments in a dry spinning metier, the filaments being collected together to form a thread and wound or twisted and wound. The thread so obtained, if desired, after knitting, weaving, or other textile operation, is then treated with aqueous hydrochloric acid of 2.5 per cent'strength for 15-30 minutes at 50-80" C. whereby decomposition of ethyl silicate takes place with formation of silica and the material acquires a pleasing dull lustre.

Example 2 A ripened viscose solution containing 8 per cent of its weight of cellulose and 0.5 per cent of its weight of silica in the form of sodium silicate, is 40 spun into an aqueous coagulating bath containing by weight 8 per cent of sulphuric acid, 1 per cent of ammonium sulphate, 13 per cent of sodium sulphate, and 11 per cent of glucose. During spinning the bath is kept at 35-40 C. and its composition maintained uniform by such. addition of sulphuric acid, ammonium sulphate, and glucm as may be required. The ccagulated filaments are brought together and led from the bath to a suitable winding or twisting and wind ing device. The yarn so produced is then fur ther processed in the manner well known in the viscose artificial silk industry.

What I claim and desire to secure by Letters Patentis:-'-

5. Process for the production of artificial filaments of low lustre, which comprises subjecting to the action of aqueous reagents artificial filaments of an organic derivative of cellulose, said filaments containing a silicate ester.

6. Process for the production of artificial filaments of low lustre, which comprises subjecting to the action of aqueous reagents cellulose acetate artificial filaments containing a silicate ester.

7. In the manufacture of materials comprising organic derivatives of cellulose by spinning proc, the step of forming silica in the materials by introducing an alkyl silicate into the spinning solution, and treatingthe formed materials with aqueous reagents.

8. In the manufacture of materials comprising cellulose acetate by spinning processes, the step of forming silica in the materials by introducing an alkyl silicate into the spinning Qlution, and treating the formed materials with aqueous reagents.

9. In the manufacture of filaments comprising cellulose acetate by spinning p, the step of forming silica in the filaments by introducing an alkyl silicate into the spinning solution and treating the formed materials with aqueous reagents.

10. In the manufacture of materials comprising cellulose acetate by spinning processes, the step'of forming silica in the materials by int-roducing an alkyl silicate into the spinning solution, and treating the formed materials with- HENRY DREYFUS. 

